RRB Group-D Model Paper 17 with answers for online practice

GIVEN:
x – y = 12 and x2+y2 = 156
CONCEPT:
Here we need to carefully look at the question and check whether (x+y)2or(x–y)2 will be applied
FORMULAE USED:
(x–y)2 = x2+y2 – 2xy
CALCULATION:
Considering the given statement
x – y = 12 and x2+y2 = 156
(x–y)2=x2+y2 – 2xy
Putting the values we get,
(12)2=x2+y2–2xy
⇒ 144 = 156 – 2xy
⇒ 2xy = 12
⇒ xy = 6
∴ Required value is 6